It has been known that a drug loaded calcium phosphate cement (CPC) block can be prepared by forming a CPC paste by mixing CPC powder and an aqueous setting solution together with a drug which may be in the form of a powder or as a solute of the solution, and molding and setting the paste into a block. The drug loaded CPC block is then implanted into a patient as a bone graft or bone substitute, so that the drug is slowly released from the block in the patient's body. Alternatively, the paste may be injected into a bone cavity or defect of a patient, which forms a hardened hydroxyapatite block in-situ. Typical examples may be found in U.S. Pat. No. 5,525,148, WO 98/16209, WO 98/16168 and WO 00/15194.
There is a long standing need for an stable and taste masked dosage form for a drug which is unstable in ambient and/or with an unpleasant taste in the pharmaceutical industry, so that the drug can be orally taken by the patients and stored for a desired period of time without substantially losing its potency. To name a few those drugs include ascorbic acid, aspirin, zinc gluconate and ibuprophen.